According to the mortality concerns will increase disidentification with a group if the group no longer provides meaning and is seen as temporary.

The answer is social identity theory When a cluster no longer shields mortality concerns by providing meaning and value, group members may dis-identify, particularly if they regard the group as temporary. While leave because Boosting self-image when a group member cannot view the group positively, membership may decrease self-esteem, promoting the person to leave. 

answer; the responsibility of all person, including civilians and contractors;